This invention relates to a head-gimbal assembly in a hard disk file. More particularly, the invention relates to routing conductors and a conductor sleeve running from a gimbal to a support arm along a load beam in the head-gimbal assembly.
A head-gimbal assembly (HGA) used in a hard disk file consists essentially of three components. The first component is a slider which features a self-acting hydrodynamic air bearing and an electromagnetic transducer used for recording and retrieving information from a spinning magnetic disk.
The second component is a gimbal which is attached to the slider. The gimbal is resilient in the slider's pitch and roll directions to allow the slider to follow the topography of the disk over which it is flying. Also, the gimbal is rigid in the in-plane directions for maintaining precise in-plane slider positioning.
The third component is a load beam which is attached to the gimbal and to a support arm. The load beam is connected to the support arm by a well known technique referred to as swaging or ball staking. The load beam is resilient in the vertical direction. This resiliency allows the slider to follow the topography of the disk. As with the gimbal, the load beam is rigid in the in-plane directions. The load beam also acts as a spring supplying a downward force that counteracts the hydrodynamic lifting force developed by the air bearing.
Electrical signals are sent to and received from the electromagnetic transducer via very small conductors. The conductors are typically twisted copper wires. There are usually two conductors, but the number of conductors may vary.
The wires are routed generally along a longitudinal axis of the load beam from the transducer to the support arm. The wires are placed inside a flexible sleeve or tube to protect them from being damaged. The conductor sleeve or tube is secured to the load beam by bendable metal tabs. HGA's typically have one metal tab at the end of the load beam nearest the slider, another around the longitudinal mid-point of the load beam and two more at the end of the load beam nearest the support arm.
The two metal tabs which secure the conductor sleeve to the load beam at the end nearest the support arm are generally formed integrally with the load beam and are formed in a U-shape by the load beam manufacturer. The U-shape of the capture tabs facilitates placement of the conductor sleeve into the tabs during assembly of the HGA. As one step in the assembly of the HGA, the U-shape capture tabs are bent closed around the conductor sleeve to prevent the conductor sleeve from escaping during subsequent handling of the HGA.
However, prior to the ball staking operation, a mounting plate is welded to the load beam. Then, during the ball staking operation, clamps are applied to certain portions of the load beam and the mounting plate. To facilitate proper execution of the ball-staking technique, the capture tabs must maintain certain clearances from the surfaces of the load beam and the mounting plate. The critical clearances are related to the thickness and size of the capture tabs with respect to the load beam and the mounting plate. If these clearances are not maintained, the capture tabs interfere with the clamps used in the ball-staking operation causing alignment errors.
Mere closure of the capture tabs around the conductor sleeve does not compress the tabs enough to provide the necessary clearances. Therefore, an additional operation must be performed. After the capture tabs are closed, they must be compressed until they provide the necessary clearances.
The compression, however, alters the substantially round cross-sectional shape of the closed capture tabs into an oblong shape. This often results in the formation of undesirable metal burrs on the capture tabs which must be removed by hand. In addition, the compression operation significantly distorts the conductor sleeve and frequently damages it. In some cases, the conductors inside the conductor sleeve are crushed and damaged as well.